الفهرس 
Anatomy of the BrainOnly 14 pages are availabe for public view
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Abstract
Background: Intracranial cystic lesions are unnatural cavities in which the continuity of the brain parenchyma is disrupted because of different pathologies such as infections and tumors containing proteinaceous fluid and/or cellular/necrotic materials.
Aim of the work: The purpose of this study is to investigate the value of DWI in differentiation of the common intracranial intraxial cystic/ necrotic lesions.
Patients and Methods: This is a descriptive study, conducted from July 2019 till February 2021. It is included twenty-four adult patients of either sex with a cystic/ necrotic intra-axial brain lesion with variable perifocal edema and rim enhancement on postcontrast study at MRI unit, radiology department, Ain Shams University (ASU) Hospital. All examinations carried out after signing the informed consent by the patient himself or his guardian if the patient is incapacitated by any means.
Results: The inflammatory lesions, the wall ADC values were not uniform. We found the lowest ADC value in contrast enhanced part of the pyogenic abscess 0.922x 10-3 mm2/s and the highest ADC wall value 1.529x10-3 mm2/s found in toxoplasmosis abscess. There was a significant difference in the wall ADC values of metastatic lesions mean ADC of contrast enhanced part was 1.32 ± 0.18 x10-3 mm2/s and 0.80 ± 0.13 x10-3 mm2/s found in PCNSL, with a cut off value, sensitivity, specificity, positive predictive value (PPV) negative predictive value (NPV) and p-value of: 1.035, 100%, 100%, 100%, 100% and 0.007 respectively. The mean ADC value of the surrounding edema in our study were measured 1.40 ± 0.11 X 10-3 mm2/s for abscess group and 1.59 ± 0.31 X 10-3 mm2/s for malignant group with insignificant p-value of 0.201.
Conclusion: Further more MR techniques may be used for discrimination brain abscess from cystic or necrotic tumors, as diffusion tensor imaging (DTI), MR spectroscopy and perfusion weighted imaging as well as positron emission tomography computed tomography (PET-CT) may be helpful. The use of these additional techniques will help to improve the accuracy of MR in differentiating brain abscess from cystic or necrotic tumors.